1. Field of the Invention
The present invention relates to an image information handling technology, and, in particular, to an image processing apparatus, an image compressing apparatus, an image decompressing apparatus, an image compressing method, an image processing method, an image decompressing method, an information processing apparatus, an information processing method, a program for causing a computer to achieve image the information handling scheme, and a recording medium storing therein the program.
2. Description of the Related Art
Recently, development in image input/output technology is remarkable. For example, a copier employs a digital information processing technology rather than an analog manner, so that various types of image handling manners are available. Furthermore, in addition to a copying function, a printer function, a facsimile function and so forth may be applied together. Such a machine is called a composite machine (MFP: multi-function printer) or so, and has been in widespread use in the market.
In such a composite machine, in order to save a memory capacity, a high-definition image compressing/decompressing technology such as that of JPEG (joint photographic experts group) 2000 may be applied. Thereby, image data read in, with a scanner is once compressed into code data, which is then stored in a memory. After that, in a reverse procedure, the code data is decompressed into image data, which is then output to a printer device. Then, the printer device performs printing operation therewith.
Further, in such a composite machine, for the purpose of reuse copy documents, printing documents, facsimile documents, or so may be once registered in a memory.
In view of such a situation, and also, in view of the necessity of increase in available memory capacity, creation of image database (image server) is advantageous in such a composite machine which thus has a capacity of storing a large amount of image data. Specifically, the image database may be built storing various types of image data while such image data is input by reading in, via a scanner or so, necessarily, along with a routine copying operation, facsimile transmission operation and so forth.
In fact, various types of devices are connected to a communication network such as the Internet recently for the purpose of utilization of the network environment for which base technology has been developed remarkably as being well known. The above-mentioned MFP is one of them, and, may not be connected to a personal computer directly but via the network. Then, in such a case, the MFP operates according to instructions given via the network, and thus, may act as a part of a total image server system.
For example, as an expected business model, by effective utilization of the functions of the MFP to the fullest extent, a server of a publishing firm which dispatches various types of image data via the Internet, may have an image database (image server) such as that mentioned above in which, in use of the MFP or so, image data is stored in a form of digital data. Then, therefrom, electronic data is dispatched free of charge or with some charge via the Internet. Especially, thanks to a high-definition image compressing/decompression technology such as that of JPEG 2000, lossless compression/decompression can be easily achieved, and, thus, each user can obtain a high-definition image reproduced on hand very equivalent to that stored in the server. Thus, such a business model may be easily achieved.
On the other hand, in such an MFP (multi-function printer), especially in a full-color MFP, a demand for improvement in printing quality of color images has been increased. Especially, a demand for achieving true black and sharp printing of black characters (letters) or black fine lines has been increased even in color images. In fact, when a black image is decomposed in terms of color, as a signal for reproducing black, respective signals of yellow, magenta, cyan, and black should be generated. However, actually, upon reproducing black by overlapping these respective primary colors, color blurring may occur due to positional error among the respective colors. Such a phenomenon may be remarkable especially in case of printing black fine lines or thin lines, and thereby, the originally black lines may not appear as those of true black or sharp definition may not be achieved, accordingly. As a result, the printing quality may be remarkably degraded.
In order to cope with such a problematic situation, the following technology may be applied, for example: Line generating components and halftone dot components are separated from color image data (referred to as image area classification or so), characters (letters) and line drawings are thus extracted from an original image, thickness or color saturation of the characters and line drawings are determined respectively, and, then, based on these determination results, predetermined image processing is performed. As to such a technology, see Japanese laid-open patent application No. H07-203198, for example. Thereby, the thickness of lines of the characters or line drawings may be changed gradually, and, thus, it becomes possible to avoid degradation in image quality which may otherwise occur upon reproduction of black fine lines/thin lines as mentioned above.
However, in such a high-definition image processing environment, assuming that an image server (image database) system is build as mentioned above as in an expected business model, as image data handled there is digital one, with utilization of features of the technology of JPEG 2000 in which lossless compression/decompression can be easily achieved as mentioned above, illegal copy or illegal tamper may be made at a user end. Such an issue in terms of copyright protection should be effectively coped with (first problem).
Furthermore, in case of performing image area classification or so mentioned above with the art of Japanese laid-open patent application No. H07-203198, information obtained there such as the determination results concerning the thickness or color saturation, which may be called ‘management information’ for managing the relevant image data, is in many case stored in a location different from a location in which the relevant image data is stored.
In fact, in case of reading an original image via a scanner of an MFP, compressing the thus-obtained image data according to the technology of JPEG 2000 algorithm, and storing the thus-compressed code data into a memory, some image degradation may occur during the compression process. Thereby, sharpness in an edge portion of an image may be degraded in the image data, for example. In case where such an edge sharpness degradation or so occurs, a problem such as erroneous detection of edge portion may occur upon reuse of the image data with a personal computer or so. If the above-mentioned ‘management information’ or so may be utilized, such a problem may be effectively solved. However, if the management information is stored in a location separately from the relevant image data, it may not be available at the occasion (second problem)
Thanks to JPEG technology, high-definition images may be easily obtained via an input device such as a digital still camera, a scanner, or so, and also, via an output device such as an ink-jet printer, a display device or so which apply the JPEG 2000 technology. According to conventional JPEG, basically in order to remove redundancy in space domain, two-dimensional cosine transform is applied.
Basically, this technology enables simply compressing and decompressing a still image. Accordingly, basically, it is not possible to manipulate an image or decompress so as to reproduce only a part of an image in a form of a compressed file. Further, basically, this technology handles image data by treating it as a flat structure, and, thus, it is necessary to completely decode the compressed code data once, for the purpose of making some modification of so on the image.
Furthermore, according to conventional JPEG, basically, along with increase in image definition or image size, in other words, increase in the number of pixels included, a time required for decompressing the relevant image data for the purpose of actually displaying the image on a display device increases accordingly. Especially, due to increase in image inputting performance of the above-mentioned input device, an image thus-obtained has an increased definition or increased size recently. Furthermore, in a technical field of handling satellite photographs or aerial photographs, a field of handling images of medical or science field, or a field of handling images of cultural property, the above-mentioned problem of increase in time required for decompressing the code data for actually displaying the relevant image on the display device or so may have already become a serious problem to be solved absolutely. According to conventional JPEG, basically, the time required for decompression is fixed regardless of the rate of size reduction which may have to be performed so as to make the thus-reproduced image adapt to the particular performance of the actually applied display device. This is because, as mentioned above, regardless of how to process the image data decompressed, the code data which was coded according to JPEG should be completely decompressed once.
In fact, it is difficult to display the entirety of an image having such an increased size or definition on a display device at hand since the particular display device has its limit of reproducing the number of pixels. Actually, as mentioned above, the image data decompressed is reduced so that the data may adapt to the particular performance of the display device applied. On the other hand, also as mentioned above, the code data should be once decompressed completely according to conventional JPEG technology. The time required for decompression depends on the number of pixels, and minutes or tens of minutes may be required in general until the relevant image can be actually displayed on the display device.
Furthermore, according to the conventional JPEG algorithm, even when a user does not necessarily wish to use the image data which is obtained from completely decompressing the given code data, the decompression should be performed completely. In the decompression process, the order of data processing cannot be controlled, i.e., a position of a given image, a color component of the image, a process of a predetermined series of processes, which should be processed first, cannot be controlled. Therefore, even a user wishes to merely obtain a grayscale image from an originally color image, or wishes to merely obtain a particular position of an original image, merely view a thumbnail image, view at high speed a series of motion picture frame images, or so, the compete decompression is needed each case according to the conventional JPEG technology.
In order to solve this problem, the applicant of the present application proposed an art by which a time required for decompression can be reduced, i.e., coded high-definition image data of still image or a motion picture made of a series of still images can be displayed at high speed. In this technology, according to a novel code sequence production function, an image area or a color component to be decompressed is defined, or the order of decompression operation to be performed is controlled, so that the image decompression can be performed efficiently. In other words, a decompression operation to be performed is defined.
For example, in an image display device, an image thumbnail is displayed often. According to the conventional art, for the purpose of displaying an image thumbnail, decompression for the entire original image is performed first, and, after that, the resolution thereof is reduced. In another method, a thumbnail is previously prepared and is stored for an occasion in which it is actually displayed. In any method, according to the JPEG standard, image compression/decompression is performed in use of a basic function of the standard or an expanded function. As the expanded function, the above-mentioned technology proposed by the applicant of the present application may be applied.
However, in case of outputting, i.e., displaying, printing or transmission of a thumbnail image, a considerable time is required when the above-mentioned method of once decompressing code data for the entire image and after that reducing the resolution thereof is applied.
In case of applying the above-mentioned method in which such a thumbnail image is stored previously, and is read out in a occasion of actual use thereof for display or so, a method may be applied in general in which the substantial data of the thumbnail image itself is written in a header portion of the compressed data of the original image as is standardized in Exif (exchangeable image file format) or so. In this method, a time required for achieving a display of the thumbnail image can be effectively reduced. However, the entire data amount of the compressed data increases accordingly by the amount of the substantial data of thumbnail (third problem).
On the other hand, the above-mentioned JPEG 2000 scheme (ISO/IEC FCD 15444-1) has been standardized as a next generation image coding scheme of JPEG. According to JPEG 2000, an image is stored with maintaining a high-definition condition thereof, and, then, a specific resolution image part or a specific image-quality image part may be extracted therefrom. Thereby, output (display, printing or transmission) of a thumbnail image or so can be easily achieved at high speed. As a result, the number of cases where such thumbnail images are actually used may increase further.
In case of achieving a display of a thumbnail image in a digital still camera or so in use of a once compressed or divided image file (code data) which is obtained through a process of the JPEG 2000, it is necessary to reduce the file size of the image data accordingly. Such a process of reducing the image file size, i.e., re-compressing the image size, or extracting a divisional part of image data once divided for the purpose of reuse thereof is performed in many cases.
In such an occasion in which a partial extracted data obtained from re-compression or division is reused, an image file of the thus-obtained partial extracted data may be copied for the use. In such a case, the remaining part of the original image may be lost as will be described later. After that, however, a desire may occur in some case in a user to reuse the entire original image file which also includes the part thereof which is once lost as mentioned above. For example, the user may wish to obtain a high-definition version or a large-size version of the image to be printed out or so in a later occasion. However, in case the user possesses only the image file of the thumbnail image which was once reduced in the file size as mentioned above, such a desire cannot be satisfied easily. Such a problem may occur not only in a case where once re-compressed image data file is taken out but also a case where once simply compressed image data is taken out partially by a user (fourth problem).